Due to the concern over the known toxicity of certain metal compounds such as lead, there has been an effort to replace percussion primers based on lead styphnate, with lead-free percussion primers.
The Department of Defense (DOD) and the Department of Energy (DOE) have made a significant effort to find replacements for metal based percussion primers. Furthermore, firing ranges and other locales of firearms usage have severely limited the use of percussion primers containing toxic metal compounds due to the potential health risks associated with the use of lead, barium and antimony.
Ignition devices rely on the sensitivity of the primary explosive that significantly limits available primary explosives. The most common lead styphnate alternative, diazodinitrophenol (DDNP or dinol), has been used for several decades relegated to training ammunition. DDNP-based primers suffer from poor reliability that may be attributed to low friction sensitivity, low flame temperature, and are hygroscopic.
Metastable interstitial composites (MIC) (also known as metastable nanoenergetic composites (MNC) or superthermites), including Al/MoO3, Al/WO3, Al/CuO and Al/Bi22O3, have been identified as potential substitutes for currently used lead styphnate. These materials have shown excellent performance characteristics, such as impact sensitivity and high temperature output. However, it has been found that these systems, despite their excellent performance characteristics, are difficult to process safely. The main difficulty is handling of dry nano-size powder mixtures due to their sensitivity to friction and electrostatic discharge (ESD). See U.S. Pat. No. 5,717,159 and U.S. Patent Publication No. 2006/0113014.
Health concerns may be further compounded by the use of barium and lead containing oxidizers. See, for example, U.S. Patent Publication No. 20050183805.
There remains a need in the art for an ignition formulation that is free of toxic metals, is non-corrosive, may be processed and handled safely, has sufficient sensitivity, and is more stable over a broad range of storage conditions.